This invention relates to improvements in the ease of movement and manipulation of catheters, guidewires and other instruments passed through catheter introducers. Catheter introducers are devices which may be placed into a patient's vascular system for angiographic, angioplastic and other medical procedures. A catheter introducer generally consists of a distally extending tube-like portion which is inserted, partially of wholly, within the patient's vascular system or other body part. The tube-like portion has a housing on the proximal end of the tube-like portion. The housing is intended to remain outside the patient's body and is provided with one or more self-sealing gaskets to enable the catheters, guidewires or other instruments (such as needles and dilators) to be inserted through the gasket, then through the tube-like portion and subsequently into the patient's vascular system or other body portion.
The catheter introducer may remain in the patient's vascular system for a period of time during a anglographic or angioplasty procedure, during which time various needles, dilators, guidewires and catheters may be inserted, manipulated and removed from the introducer. During these activities the catheter, guidewire or other instrument is moved through the self-sealing gasket contained in the proximal fitting. The self-sealing gasket ideally has the dual desirable characteristics of providing a tight seal around the instrument inserted through the gasket to prevent the escape of blood or other fluids from the patient while at the same time not being so tight that the free movement of the instrument is impeded. Ease of movement is important because, as is well known in the art, a physician performing a procedure will rely on the "feel" of the catheter or guidewire as it is advanced through the patient's vascular system. The "feel" is important because the feedback a physician receives is used to guide the guidewire or catheter through the patient's sometimes tortuous vascular system. Thus, a compromise must usually be struck between sealing ability and ease of movement.
Prior art devices have attempted to address the desirable characteristics of sealing ability and ease of movement by providing lubrication of the self-sealing gasket by impregnating the gasket with a lubricating oil. U.S. Pat. No. 4,798,594 to Hillstead discloses impregnating the gasket with a free silicone lubricating fluid. While this method may be somewhat effective over the short term, the amount of lubricating fluid contained within the gasket will dissipate after only a few catheter or guidewire exchanges as the catheter or guidewire picks up an amount of oil and depletes the oil within the gasket. In a anglographic or angioplasty procedure, for example, there may be as many as 7 or 8 exchanges. The limited amount of lubricating fluid in a gasket similar to the Hillstead design results in the fluid being depleted after only 3 or 4 exchanges, thus decreasing the ease of movement in subsequent exchanges.
Other prior art devices have included a lubricating fluid-containing portion in the proximal housing. An example of this arrangement is illustrated in U.S. Pat. No. 5,104,389 to Deem et al. Deem et al. disclose a catheter introducer housing which has a foamed elastomer material located distally of a self-sealing gasket. The patent discloses introducing a hydrophilic lubricant material on the elastomeric partition member or gasket as well as on the foamed elastomer material.
Another prior art device, U.S. Pat. No. 5,098,393 to Amplatz et al., discloses a catheter introducer in which the housing includes a sponge material which contains a lubricating fluid. The catheter or guidewire, as in Deem et al., passes through the sponge or foamed material and picks up lubricating fluid to ease the movement of such instruments. While both Deem et al. and Amplatz et al. provide a means for lubricating instruments passed through the gaskets, the presence of a foamed material or sponge would impede the movement of such instrument and negate to some extent the benefit received by using lubricating fluid. In addition, the location of the lubricating fluid distally of the gasket does not optimally lubricate a catheter or guidewire which is inserted through the proximal end of the gasket because there is no lubricating fluid to ease the entry of such catheter or guidewire at the proximal end of the gasket.
In yet another prior art device, illustrated by U.S. Pat. No. 4,649,904 to Krauter et al., an endoscopic seal discloses the use of lubricant in a cavity located between a first outer and second inner distally positioned seal or gasket to facilitate the passage of a biopsy forceps or other tool through the outer and inner seals. In Krauter et al., as in Deem et al. and Amplatz et al., the source of lubricating fluid is located distally of the outer surface of the gasket such that a catheter or guidewire entering the hub or fitting is not lubricated as it passes through the first gasket. In addition, the Krauter et al. device requires two seals which act to contain the lubricating fluid, and the fluid is subject to escape into the body of the endoscope if an instrument is passed through the first and second seal or gasket.
Thus, while prior art devices recognizes that lubrication of catheters and guidewires is desirable, each of the prior art devices has certain deficiencies discussed above. It is among the general objects of the invention to provide an improved catheter introducer which provides for efficient lubrication of the gasket over a number of catheter and guidewire exchanges by providing a reservoir of lubricating fluid proximally of the gasket.